Data from: Indirect genetic effects and the genetic bases of social dominance: evidence from cattle

Genetic studies of social behaviour have currently received new impetus from models including indirect genetic effects of social partners. This study aimed at investigating the contribution of conspecifics in social dominance, considered as response of dyadic interaction i.e., winning (dominant individual) or losing (subordinate). A genetic correlation of -1 is expected between the attitude to win and the attitude to loose, and because a population always accounts for half winners and half losers, the heritability of the dominant status should be close to zero. Specifically, social dominance was studied in Aosta Chestnut and Aosta Black Pied (Bos taurus) breeds; alpine rustic cattle famous for traditional tournaments where pairs of cows assess dominant status in bloodless fights. The outcomes of 25,590 dyadic interactions performed by 8,159 individuals in 11 years were analysed by applying a classical quantitative model and models including indirect effects. Data were analysed via Bayesian approach on a threshold trait. The assessment of variances revealed a genetic correlation of -0.976 between direct and indirect genetic components. The heritability measured on a liability scale was 0.122 for direct phenotype, but decreased to 0.014 when the total heritable variance (TBV) was considered. The trend of EBVs showed that total TBV was constant over the years, even though its direct component increased and the indirect part decreased. This result confirms the relevance of IGEs on social behaviour and the assumption that the mean individual social dominance cannot evolve within a population, due to the evolutionary constraints imposed by the "social environment".当前，包含社会伙伴间接遗传效应（indirect genetic effects, IGE）的模型为社会行为遗传学研究带来了新的研究动力。本研究旨在探究同种个体对社会支配地位的贡献——社会支配地位被视为二元互动的结果，即获胜（支配个体）或落败（从属个体）。预计获胜倾向与落败倾向之间存在-1的遗传相关；且由于种群中胜者与败者各占一半，支配地位的遗传力应接近0。具体而言，本研究以奥斯塔栗色牛与奥斯塔黑白花牛（Bos taurus）两个品种为研究对象，这两类阿尔卑斯乡土牛以传统格斗赛事闻名，赛事中母牛两两通过无血搏斗评估支配地位。本研究对11年间8159个个体完成的25590次二元互动结果进行分析，分别采用经典数量遗传学模型与包含间接遗传效应的模型开展分析。数据采用贝叶斯方法按阈值性状进行分析。方差组分评估结果显示，直接遗传组分与间接遗传组分间的遗传相关为-0.976。以易感性尺度计算，直接表型的遗传力为0.122；但当考虑总遗传方差（total heritable variance, TBV）时，遗传力降至0.014。估计育种值（Estimated Breeding Values, EBVs）的变化趋势显示，尽管直接组分逐年上升、间接组分逐年下降，总TBV却保持稳定。本研究结果证实了IGEs对社会行为的重要性，同时验证了如下假设：由于‘社会环境’施加的进化约束，种群内个体的平均社会支配地位无法发生进化。